Distillation of hydrocarbons



Feb. 2, 1932.

F. A. HOWARD Q 1,843,560

DISTILLATION OF HYDROCARBONS Filed July 10 1924 Coouuc. Con

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Patented Feb. 2, 1932 [TED STATES PATENT OFFICE FRANK A. HOWARD, 0F ELIZABETH, NEW JERSEY, ASSIIGNOR DO STANDARD OIL DE- VELOPmT COMPANY, A. CORPORATION OF DELAWARE msrnna'rxon or nrnnooannons Application filed July 10, 1924. Serial No. 725,154.

This invention relates to the distillation of hydrocarbons, and will be understood from the following description, taken in connection with the accompanying drawings in which Fig. 1 represents in sideelevation, partly in section, one form of apparatus which may be employed, and Fig. 2 is a fragmentary vie showing distilling means.

In the customary practice of distilling petroleum, the crude oil is heated to a vaporizin g temperature and a light distillate is taken 011', the temperature is further raised and a heavier distillate is taken oif, and so on progressively, the temperature being successively higher and the distillate cuts successively heavier. Toward the end, in taking off lubricating distillate cuts there is increasing difficulty in limiting damage from overheating, and resort is usually had at this stage to the expedient of introducing steam or reducing pressure. Even at best, in the operation of prior methods more or less destruction of the lubricating constituents occurs through overheating.

In accordance with my invention, the (listi1lation conditions are so arranged as to produce a relatively low boiling material containing the lubricating oils by vaporizing off collectively the light constituents and heavy constituents in one wide cut. This may then be fractionated at temperatures below that at which objectionable decomposition occurs.

Referring more particularly to the drawings, the numeral 1 designates a heating chamber fired by any convenient means and containing a conduit or coil 2 through which oil is'passed to be heated. Steam may also, if desired, be introduced into the oil in the conduit through a connection (not shown). From the heating conduit,a connection con: taining a valve 4 leads to a vaporizing chamher 3. Steam may be passed through a suitable connection into this chamber, instead of into the conduit, if desired.

The vaporizing chamber contains a cooling 1 coil 5,-a' collecting pan 6 connected by line it? with a receiving tank 11. a final cooler 12. and a collecting tank 13. The vaporizing chamher is connected near the top thereof by line M with a barometric condenser 15, wherein any steam or light oils are practically completely condensed and pass into sump 16. The barometric condenser is also connected by line 17 with asurface cooler 18 wherein any remaining condensable vapors are separated out and removed as condensate by pump 20.

The entire system, exclusive of the heating coil, is maintained under suitable pressure, preferably below atmospheric pressure, by means of pump 9 joined by line 19 to the surface cooler 18. The pressure may vary rather widely. Goods, results are ordinarily obtained when the absolute pressure corresponds to a mercury column of about 2 inches. The condensate receiving tank 13 or the receiving tank 11 may also'be joined by a line direct to the vacuum pump, if desired, but ordinarily the construction shown operates satisfactorily to accomplish the object in view.

In Fig. 2 there is illustrated a still 21 which is forwarded from any desired source through the heated conduit2andthe temperature of the oil is-raised sufiiciently to produce the subsequent vaporization desired, but without attaining substantial cracking range. The precise temperature will vary somewhat with the particular oil being operated upon. I As an illustration. the oil temperature at the heating conduit'outlet may be maintained around 650 F. Passingfrom the conduit, the oil is released into the yaporizing chamher 3 where under the diminished pressure or vacuum maintained, a flash vaporization occurs due to the contained heat in -the oil. This results in producing one wide cut containing all constituents from the lowest boilup to the heaviest that can be distilled without substantial cracking.

Since the low boiling constituents reduce the fiective boiling point iior the entire cut,

may pass to a fractionating tower (not shown), which may be of plate rectifying column type or simpler type as preferred. Heat may be supplied by steam coils at the bottom of the tower. A lubricating stock condensate may be first taken off and successively lighter fractions condensed in the further zones of condensation.

The following example is illustrative of one method in which the invention may be..practiced. A reduced crude oil, such as reduced Colombia crude having an A. P. I. gravity of about 16.5, is passed through the coil 2 and enters the tower 3 at a temperature of 710 to 720 F. The temperature of the oil in the bottom of the tower is about 647 F., the temperature of the vapor stream leaving the tower is about 236 F., and the temperature of the condensate flowing through line 10 is about 403 F. This condensate'is composed of one wide cut containing hydrocarbons condensing in general between 236 F. and 647 F. It has an A. P. I. gravity of about 22.8, a Saybolt viscosity of about 268 seconds at 100 F., and a dash point of about 335 F. The absolute pressure in the tower is equivalent to about one inch of mercury. The lubrieating distillate is withdrawn from tank 13 and separated into the desired fractions in any suitable manner.

"While the vapors may be fractionally condensed as described above, I usually prefer to condense them in one collective condensate as described and distill oft from these the lighter constituents to effect the desired further separation, including the segregation of lubricating oils.

\Vhere employing a crude petroleum having a considerable gasoline content, it is sometimes desirable to distill off in the usual mannor a part or all of the gasoline before introducing the oil into the heating conduit.

The invention is not limited to the specific embodiment referred to for the purpose of explaining the inventive principle. Various alternative arrangements of procedure and apparatus may be made within the scope of the appended claims.

What I claim is: a

1. The improvement in the art of distilling hydrocarbon oil containing lubricating fractions together with lighter constituents, which comprises heating the oil to a high temperature short of substantial cracking in a conduit of restricted cross-section, passing the hot oil into the lower portion of an enlarged vertical zone maintained under pressure slithciently reduced below the pressure in the conneeaaeo duit to permit flash vaporization, by the contained heat of the oil only, of one wide cut containing lubricating fractions together with lower boiling constituents which reduce the efiective distillation temperautre, and condensing said lubricating fractions within the enlarged vertical zone.

2. The improvement in the art of distilling petroleum containing lubricating fractions together with lighter and heavier constituents, which comprises passing the petroleum through a heated conduit of restricted crosssection to raise it to a high temperature short of substantial cracking, thence into the lower portion of a vertical vaporizin chamber maintained under a pressure less t an atmospheric, heating the chamber only by the heat of the entering oil, vaporizing in the chamber one wide cut containing all constituents from the lowest boiling to the highest boiling that are removable at the temperature and pressure of the operation, condensing the Wide cut with the exception of the lowest boiling components, within the chamber, and collecting the condensed wide out without permitting the same to commingle with the heavier constituents.

3. The improvement in the art of distilling petroleum oil containing lubricating fractions together with lighter and heavier constituents, which comprises passing the oil through a heated conduit of restricted cross-section to raise the oil to a high temperature short of substantial cracking, thence into the lower portion of vertical vaporizing chamber main; tained under a pressure less than atmospheric, heating said chamber by the heat of the entering oil only, vaporizing in said chamber one wide cut containing all constituents from the lowest boiling to the highest boiling that are removable at the temperature and pressure of the operation, condensing the wide cut with the exception of the lowest boiling components, within the chamber, collecting the condensed wide cut in the chamber at a point above that at which the oil enters the chamber, withdrawing the condensed wide cut, and separately removing the residue of heavier constituents from said chamber.

FRANK A. HOWARD. 

